Parts | Days | Selection | Search | Downloads | Help
UP: Fachverband Umweltphysik
UP 1: Atmosphäre und Klima I
UP 1.3: Talk
Monday, March 26, 2007, 10:00–10:15, H48
Long-Path-DOAS measurements of aromatics,polyaromatics and HOx precursors in Mexico City — •André Merten1, Rainer Volkamer2, Phillip Sheehy2, and Ulrich Platt1 — 1Institut für Umweltphysik, Im Neuenheimer Feld 229, 69120 Heidelberg — 2MIT, Cambridge, MA 02139
Two Long-Path-DOAS instruments were installed in Mexico City in March 2006 as part of MCMA-2006 field campaign to measure VOC and radical precursors of HOx (Glyoxal, HCHO, HONO) and other species in a megacity urban environment. A particular focus of the combined DOAS set-up was to assess horizontal gradients of species that were measured by both instruments on different spatial scales and directions. The DOAS#1 telescope primarily measured aromatic volatile organic compounds (VOCs) as precursors for secondary organic aerosol (SOA) formation, among other species like O3 and SO2. Measured VOCs included benzene derivatives e.g. toluene, styrene, phenol, cresols and xylenes, as well as two ring aromatic compounds,naphthalene and methylnaphthalene. Episodes of remarkably high concentrations of toluene (e.g.190 ppb) and styrene (14,5 ppb) were observed for selected direction, probably due to plumes of solvents moving through the city. DOAS#2 was dedicated mainly to measure HOx radical precursors like Glyoxal, HONO, HCHO and Ox. Glyoxal, a product of VOC oxidation, showed maximum concentrations between 0.5 and 1.4 ppb. HONO measurements results in night time maximal values about 9ppb and 0,2ppb for day time and clear sky conditions.